bitter

A bitter is a single wrap or turn of rope, cable, or chain around a bitt, the vertical post or pair of posts fixed to a ship's deck used to secure mooring lines. When a ship is tied to a dock or another vessel, the mooring cable is wound around the bitts in one or more turns to provide friction and holding power. Each complete turn is counted as one bitter.

The number of bitters applied depends on the breaking strength of the line and the load it must hold. A large steel cable under tension from a heavy vessel might require two or three bitters to be secure, while a lighter synthetic line might need only one. The turns are laid carefully so each wrap sits parallel to the previous one, building friction without crossing or jamming. Proper spacing ensures that the cable can be released quickly if necessary.

Technique and Terminology

A bitter round the bitts is different from other knots or hitches because it relies on friction between the cable and the post rather than on the geometry of a knot. Dock workers and deck crew use the term to coordinate their work: a watch standing on deck might call out 'take two bitters' to another crew member to indicate how many turns to apply. The term also appears in the phrase 'to the bitter end', which refers to the final end of a cable after all the good usable length has been paid out.

Modern container ships and tankers have powered winches that handle most mooring work, but the principle remains unchanged. On smaller vessels, tugs, and in some emergency situations, manual application of bitters is still necessary. The friction holding power can be surprising: three bitters of a 16 millimeter wire rope can hold a considerable load because the wrap multiplies the mechanical advantage.

The word bitter appears in ship logs and mooring instructions dating back centuries, long predating the modern bitt hardware. Its origin likely comes from the Dutch word 'beting', relating to the securing or binding action. Today it remains essential vocabulary for anyone working with vessel mooring, dock operations, or maritime safety, even as equipment and methods have become more mechanical.